70 fad ile DeclinatiouKrſtis cke Horizontal Line; the ſecond, the Perpendicular Line, croſſingthe Horizontal at Right Angles; the chirds the Axis of the Plane, eroſſingboth the Horizontal Line, and his perpendicular, and the Plane it ſelf atRight Angles. 5 a 3 f

The Perpendicular Line doch help to find che Inclination of che Plane,as before; the Horizontal, to find the Declination; the Axis, to givedenomination unte the Plane. f

For example: In a Vertical Plane in the Fundamental Diagram, repre-ſented by EL W,. che Horizontal Line is EC W, che ſame with che Lineof Eaſt and Weſt, and therefore no Declination. The Perpendicular croſa-ſing it is C the ſame with che Vertical Line, drawn from the Center tothe Zenith, right unto the Horizon, and therefore no Inclination. TheAxis of the Plane is S CN, the ſame with the Meridian Line, drawn fromthe South to the North, and accordingly gives the denomination to tliePlane. For the Plane having two Faces, and che Axis two Poles, S andN, che Pole 8 falling directly into the South, doth cauſe that Face towhich it is neze, to be called che South Face; and the other Pole at N,pointing into the North, doch give the denomination to the other Face,and make it to be called the North Face of this Plane.

In like manner, in the Declining Inclining Plane in che FundamentalDiagram, repreſented by B E D, the Horizontal Line is BC D, whichcroſſetli the prime Vertical Line ECW, and therefore it is called2 Declining Plane, aeccorcling to the Angle of Declination ECB orWC D. The Perpendicular to this Horizontal Line is CE, where thepoint P falleth in the Plane Q H perpendicular to the Plane propoſed,between the Zenith and the North part of the Horizon; and therefore itis called a Plane inclining to the Northward, according to the Arłk FOor the Angle EC Q. The Axis of the Plane is here repreſented by theLine CK, where the Pole K is 90 gr. diſtant from the Plane, and ſo is asmuch above che Horizon at H, and the other Pole as much below the Ho-riron at Q. as the Plane at F is diſtant from the Zenith: And this Pole Khere falling between the Meridian and the prime Vertical Circle into theSouthweſt part of the World, this upper Face of che Plane is thereforecalled the South-weſt ace, and che lower the North- eaſt Face of thePlane. 1 1 5 a 8

The Declination from the prime Vertical may be found by the Needlein the uſual Inclinatory Quadrant, or rather by comparing the Horizon-tal Line drawn upon the Plane, with the Azimuth of che Sun, and theMeridian Line, in ſuch ſort as before we found che Variation of the 11

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